Arteriosclerosis is a vascular disease characterized by constrictions, generally referred to as stenoses, which result from the build-up of plaque on the interior wall of a blood vessel. Platelets may aggregate on the diseased blood vessel and form clots, which further occlude the lumen.
Arteriosclerosis is commonly treated by balloon angioplasty. Prior to treatment, it is often desirable to have an accurate visual picture of the affected area or to gather blood velocity data in order to assess the obstruction. After treatment, imaging and velocity information is useful to determine whether the stenosis has been successfully removed.
Ultrasound imaging catheters and guidewires can provide an image of the intraluminal anatomy. These devices include a transducer that emits ultrasound beams in a direction generally transverse to the catheter axis. The ultrasound energy reflected from the lumen wall is detected and processed to provide the image.
Doppler flow catheters and guidewires are used to measure the velocity of fluid within a body conduit. These devices have a transducer that emits an ultrasonic beam generally along the device axis. The ultrasonic energy reflected from the flowing fluid is detected and Doppler-analyzed to determine the velocity.
Imaging and Doppler data have been obtained by delivering an imaging catheter over a Doppler guidewire or by using a catheter with multiple transducers, some of which are dedicated for imaging and some of which are dedicated for Doppler measurement. The imaging data can be processed to determine the cross sectional area of the vessel lumen. Combined with the flow velocity data from the Doppler measurement, the blood flow volume can be computed.